Method of distilling coal



Dec. 5, 1933. STEVENS 1,938,123

METHOD OF DISTILLING COAL Filed Oct. 18, 1930 2 Sheets-Sheet l IN VEN TOR.

ATTORNEYS.

Dec. 5, 1933. H. STEVENS METHOD OF DIST'ILLING COAL Filed Oct. 18, 1930 2 Sheets-Sheet 2 IN VEN TOR. Mm

A TTORNEYS.

atented Dec. 5, i933 arra METHOD OF DIS'EELLING COAL Harold Stevens, Cincinnati, @hio, assignor, by mesrne assignments, to Harold Stevens, trustee Application Zl ctober l8, 1934i. Serial No. $9,535

)1 Claim.

Qne of the primary objects of my invention is to utilize a minimum ground area and to obtain a maximum return from a given plant investment.

More particularly it is an object of the invention to distill a relatively large quantity of coal in a relatively short time and to obtaina relatively large quantity of gas.

Another object of the invention is to simplify, facilitate and expedite the charging of the coal and the removal of the coke or semi-coke as the case may be.

it is still another object of the invention to obtain a substantially uniform and a good quality of gas.

A further object of the invention is to so apply the heat and to so withdraw the gases evolved that there is a minimum degradation of the products from cracking.

My invention also contemplates the utilization of the full volume 01 the retort.

Still another object of the invention is to simplify the heating and to facilitate the application of the heating element or elements.

I obtain the foregoing by means of a method and apparatus which I have illustrated in the preferred form in the accompanying drawings, wherein-- Fig/ l is a vertical section through a retort embodying my invention.

Fig. 2 is an enlarged cross sectional view through the retort taken on the line 2--2 of Figure 1 roughly illustrating what occurs during the process of distillation.

In carrying out my invention I employ a vertical retort or bench ofvertical retorts, each retort being relatively long or tall as compared with its diameter, sothat the retort will contain a large quantity of coal while still occupying a relatively small ground area. I also prefer that the retort shall be circular in cross section as with the character of heating employed this shape gives the best results, in addition to effecting an economy by virtue of the reduction in the number of shapes of brick required. The vertical disposition of the retort also enables me to completely fill the space with a charge and with the character of heating employed practically the entire volumetric capacity of the retort can be effectively utilized.

in addition, the vertical disposition of the retort greatly facilitates the handling and the charging of the raw coal and the discharging and the handling of the coke and simplifies the mechanism needed, as well as reduces the time required for these operations.

By using a vertical retort I can carry it to any desired height and obtain greatly increased. capacity much more economically than it is possible to obtain large capacity in horizontal retorts; and with the character of heating em= ployed I can heat a larger quantity of coal and, therefore, secure a correspondingly large output in a relatively short period of time.

Referring now to Fig. 1, it will be seen that I have therein shown a retort 7 of the general character described. The particular structure of the retort forms no part of this invention. The retort is closed at the bottom by a door 8 and is provided at the top with means for delivering the charge (not shown). Before charging I introduce an electrical resistor element 9 which is composed of coke or a tube filled with coke or similar material. This starting fuse or resistor is preferably introduced through a hollow electrode 10, preferably located at the top of the retort and extending some distance down. into the charge. The lower end of the resistor makes contact with the electrode 11 which may so be carried in the door. The current may be regulated, for example, by a transformer where alternating current is employed, or by a motor generatorset where direct current is employed.

With the resistor in place the coal is charged and the current is turned on, the electrodes and the resistor providing a definite path for current within and through the mass of coal. It will be understood that the electrodes are suitably insulated and that the fire brick lining of the retort, at the temperatures normally obtaining, serves to electrically, as well as thermally, insulate the charge. The resistor becomes heated through its resistance to the passage of current and heats the contiguous coal and cokes it, the heat advances progressively'outwardly and radially through the mass. Those portions of the coal which become coked function as additional resistor means. With a circular cross section for the retort and a centrally located heating element or centrally located cluster of resistor elements where a retort of larger cross section than that shown is employed, the heating proceeds at a uniform rate radially and all the coal, circumferentially considered, is brought to the same temperature at practically the same time.

Referring now more particularly to Fig. 2, I have therein illustrated what occurs during the progress of the process. In starting the current applied raises the starting resistor to about 900 coking temperature, i. e., approximately 900 C.

The water content of the coal is driven off ahead of the high heat in an annular zone which progressively moves outwardly with increasing diameter. In Fig. 2 the cross section indicates conditions about midway of completion of the process and the reference numeral 12 indicates the annular band of raw coal surrounding the band 13 in which the water content of the coal is being driven off. The next band 14. indicates the zone in which low temperature distillation is taking place and where the light oils are being driven off. The next band 15 indicates the zone in which the heavier constituents of the coal are being evolved and the band 16 indicates a zone in which the coal has been coked. This is, of course, only diagrammatically indicated in the figures and it will be understood that the zone is moved outwardly as the process continues until eventually all of the coal is coked.

During the process the gases evolved are being withdrawn at any one of a number of suitable points and they, generally speaking, do not pass over material having a temperature higher than that at which the gases were evolved. For the most part the gases pass over relatively cooler portions of the charge, giving up a large part of the sensible heat. Thus a good quality of gas with a minimum amount of degradation, due to cracking, is obtained. In the drawings I have shown a number of gas outlets 17, but I prefer to take the gas off at the lower portion of the retort.

The liquids are withdrawn from the bottom of the retort through the pipe or pipes 18, the door being made convex for this purpose.

The heating is regulated by a cut-of! so that the outer portions of the mass of coal are heated by the sensible heat of the remaining portions, and thus coked.

If it is desired to operate essentially on a low temperature distillation basis, then the current is regulated so as to produce a resistance core of any diameter desired and maintained at such value, whereupon coking will not proceed outwardly beyond the desired point and the coal surrounding the core will not be a conductor of electricity and such coal will be distilled at relatively lower temperature. The solid product of such portion will be semi-coke characteristic of low temperature distillation whereas if the coking be carried throughout the mass, the solid product will be a coke characteristic of high temperature distillation.

However, the nature of the process, even if the coking be carried throughout the mass, is such that certain of the products are like those produced in high temperature distillation, while others are like those produced in low temperature distillation. For example, in such case the coke will be high temperatur coke, but there two nested sections with a slight space therebetween to receive non-conducting material and it is also desirable to lock the bricks against undesired displacement in heating and cooling.

The lining is inclined slightly inwardly and upwardly so the change can be readily discharged after distillation. Around the lining and between it and the metallic shell is a lining 19 of dense material of monolithic character (such as concrete or cement) which serves to prevent the liquid condensation products which are good conductors from reaching the shell.

If desired horizontal layers 20 may be disposed in the charge at various elevations and preferably opposite -poinm of gas take-01f, so as to minimize degradation by providing short paths of travel from the points of gas liberation to the points of take-01f. The layers tend to prevent the formation of a continuous plastic wall around the hot zone. Material such as coke may be employed for the layers, although a non-conductible material will serve.

The size of the pieces in the various zones shown in Fig. 2 is only for purposes of illustration and is not to be taken as actually representative. I also may make the refractory wall of an inner portion 21 of refractory material, and a surrounding portion of more highly refractory material, followed by the dense filling and the metallic shell.

Attention is called to the fact that various features herein disclosed are described and' claimed in one or more of the following of my copending applications: Serial No. 489,530, filed October 18, 1930; Serial No. 489,532, filed October 18, 1930; Serial No. 489,534, filed October" 18, 1930; and Serial No. 489,536, filed October 18, 1930.

I claim:

The process of coking coal in a retort adapted to contain an elongated column of coal of substantially circular cross section, which includes passing an electrical current through the coal to be coked in a central region thereof from end to end of the column, progressively passing an electrical current through progressively coked portions of the coal surrounding the portions first coked, to carry out the coking operation progressively from a central region radially outwardly toward the wall of the retort, cutting oil? the flow of current through the coke prior to the time when a peripheral layer of coalhas been coked, and coking said peripheral layer by the sensible heat of the coke already formed.

HAROLD STEVENS. 

